Mammary nonmuscle myosin II (NM II) is important role in cancer cells migration. LPA is well known as factor provoking diverse cellular responses including migration, chemotaxis, and invasion. So, we examine the role of NM II regulated by LPA in cancer cell migration. LPA induces migration by activating the LPA1 receptor which promotes phosphorylation of the 20kDa nonmuscle myosin II light chain through activation of Rho kinase (ROCK). LPA-induced migration and invasion are attenuated by specific inhibitors including the C3 cell-permeable transferase and the ROCK inhibitor, Y-27632. We demonstrate that NM II plays an important role in LPA-induced migration and invasion by inhibiting its cellular function with blebbistatin and shRNA lentivirus directed against the NM II-A or NM II-B heavy chain, to stably silence NM II-A and NM II-B expression. Inhibition or loss of either NM II-A or NM II-B in 4T1 cells results in a decrease in migration and invasion. Restoration of the expression of NM II-A or NM II-B also rescued LPA-induced migration. Thus, these results suggest defined pathways for signaling through the LPA1 receptor to promote LPA-mediated NM II activation and subsequent cell migration in the breast cancer cells.